Power transmission for motor vehicles



Oct. 19, 1954 MAYBACH ETAL 2,691,901

POWER TRANSMISSION FOR MOTOR VEHICLES Filed Dec. 28, 1949 4 Sheets-Sheet 1 '41 17 Fig. 1

Oct. 19, 1954 K. MAYB ACH ETAL POWER TRANSMISSION FOR MOTOR VEHICLES 4 Sheets-Sheet 2 Filed Dec. 28. 1949 1954 K. MAYBACH EI'AL POWER TRANSMISSION FOR MOTOR VEHICLES 4 Sheets-Sheet 3 Filed Dec. 28, 1949 Fig. 7

Fig. 9

Oct. 19, 1954 K. MAYBACH ET AL 2,691,901

POWER TRANSMISSION FOR MOTOR VEHICLES Filed Dec. 28, 1949 4 Sheets-Sheet 4 Patented Oct. 19, 1954 2,69l,9tl

POWER TRANSMISSION FOR MQTOR VEHICLES Karl Maybach and Hermann Gros, Friedrichshafen, Bodensee, Germany; said Gros assignor to Maybach-Motorenbau G. m. b. H., Friedriclishafen, Germany, a German firm Application December 28, 1949, Serial No. 135,402

Claims priority, application Germany December 30, 1948 8 Claims. (Cl. 74-4555) The invention relates to power transmissions for motor cars having a mechanical change speed gear for a plurality of speed ranges, a hydraulic transmission for the lowest speed step or the lowest speed steps, and an auxiliary power device for shifting the change speed gear. The invention is intended to be used especially in such cases in which heavy cars have to overcome high and often changing road resistances and speeds, necessitating frequent and troublesome changing of the gears and in many cases in which the operator cannot determine operation of the car by his ear, as is the case, for instance, with motorized rail cars and locomotives and with great busses.

According to the invention a hydraulic transmission is provided for a certain number of speeds. In a fm-ther development of the invention the hydraulic transmission is constantly kept filled with an operating liquid and is arranged between clutches adapted to be engaged or disengaged when changing into certain speed steps.

In conventional power transmissions having mechanical change speed gears and hydraulic transmissions, the shifting in or out of the hydraulic transmission proceeds too slowly, because filling and emptying of the transmission takes too much time causing long interruptions in tractive power when the car operates at lower speeds and causing reduction of car velocity. Because of the filling and em tying of the hydraulic transmission, the temperature of the operating liquid and the performance of the transmission is subject to considerable limitations, as most of the oils when used above certain temperatures tend to form vapor which causes insufficient power transmission. Although conventional devices for controlling hydraulic transmissions avoid a number of these drawbacks, they require an awkward and expensive arrangement.

Shifting in or out the hydraulic transmission according to the invention causes no interruption of the tractive power and no reduction of car velocity. The invention provides an e2-;- traordinarily powerful and extremely fool-proof power plant at low cost and makes better use of the capacity of the prime mover than conventional arrangements. The clutches for the hydraulic transmission may be comparatively small. When shifting the mechanical speed gears, the

usual interruptions in tractive power will occur, but as these changes are not made before a car velocity of 20 to 26 miles per hour is reached, they have no undesired effect on the velocity or on the operation of the car, but assure the good gear eificiency inherent to the exclusively mechanical drive.

In an especially advantageous and simple embodiment of the invention the hydraulic transmission is connected when using the lowest gear speeds and is disconnected at higher gear speeds. The drive may be transmitted through the hydraulic transmission directly to the car wheels or, in a further development of the invention, the hydraulic transmission may be use in combination with the lowest speed step, i. e. at the highest transmission ratio of the change speed gear. When disconnecting the hydraulic transmission, depending on its construction, the speed of the driving engine may be reduced by, say, 15%, according to the ratio between the primary speed and the secondary speed of the hydraulic gear transmission.

An auxiliary device is provided for effecting gear shifting by an auxiliary power, for instance by oil pressure so that the driver need not do any gear shifting. In a further development of the invention a control completely and without error answering the requirements and consequently being on time and providing the needed forces during the gear shifting operation is eifected by an automatic gear shifting device by which the changes, especially those from the operation with the hydraulic transmission. to mere mechanical drive, but also the changes between the steps of the change speed gear are prepared and controlled in response to one or several operating values as: car velocity, number of revolutions of the motor, torque of the motor, load.

According to the invention a friction clutch is inserted in the direct drive of the change speed gear and another friction clutch is provided in the drive for the hydraulic transmission. An over-running clutch, for instance a claw clutch whose claws have inclined faces is arranged after the hydraulic transmission. Instead of the friction clutch provided in the more mechanical drive a claw clutch may be used.

After the hydraulic gear a free-wheeling device which needs no control apparatus may be provided instead of the over-running clutch.

With a power transmission according to the invention it is of special advantage to arrange a free-wheeling device between the driving engine and the clutches for simplifying the shifting devices. In that case the number of revolutions may automatically and instantly decrease upon shutting off the fuel supply or when an engine defect occurs. Thus, it is not necessary to drive the engine by means of the mechanical connection with the vehicle drive at a detrimental speed.

As the hydraulic transmission, after having been disconnected, is held in filled state, a constant immediate readiness for operation, and consequently faster shifting is obtained. The hydraulic transmission is mainly used for starting or for slow operation, as for switching of railway cars. Connection and disconnection of the hydraulic transmission is effected at so low a car speed that the hydraulic losses below this speed are of no great consequences. The highest tractive power ever possible are attained.

In a further development of the invention a device for dividing the power is provided which, at low car speeds, causes portion of the power of the driving engine to be transmitted by the hydraulic transmission while the other portion is directly transmitted, the hydraulic transmission being disconnected for the mechanical drive. At low car velocities the power is transmitted to the car as well by the hydraulic transmission as merely mechanically. It is therefore not necessary to design the hydraulic transmission for the highest output as it transmits only a certain portion thereof which portion is determined by the construction of the dividing gear; the clutches and other connected parts may be made smaller and cheaper. This is especially of advantage with regard to the friction clutches which transmit only a fraction of the power which must be transmitted in conventional mechanisms. By avoiding a portion of the hydraulic losses, an increase in output, a saving in fuel and a decrease of the dimensions of the radiator is attained.

By adequately dividing the flow of power through the transmissions the speed of the engine is reduced and automatically no tractive power will occur which exceeds the adhesion of the car wheels.

An epicyclic gear is preferably used for dividing the flow of power, for instance a gear having pinions which in mere mechanical gear steps are blocked by connecting the sun gear with the planet carrier or with the ring gear. The power dividing gear considerably reduces the engine speed at the same output relatively to the drive through the hydraulic transmission alone, the hydraulic losses being lower because of the smaller amount of power transmitted.

The invention provides an extremely advantageous control for the shifting operations. Changing from operation with the hydraulic transmission to the mechanical drive and vice versa is performed without interrupting the tractive power, the clutches of one drive only being disengaged while those of the other drive are engaged. Besides, according to the invention, the control of the clutches for the direct drive as well as of those arranged ahead of the hydraulic transmission depends on the shifting stroke of the over-running clutch which is arranged after the hydraulic transmission. The operation of these control devices is preferably hydraulic. For example, when changing from the drive by means of the hydraulic transmission into the merely mechanical drive, the clutches are so controlled that the control means for disengaging the clutches of the hydraulic transmission are not prepared or do not begin to operate before the clutch of the mere mechanical drive begins to be engaged. The shifting stroke of one clutch is delayed relatively to that. of the other clutch so that there will be a divisional drive for a short time. An interruption in the transmission and, consequently, of the tractive power to the vehicle does not occur. Only the number of revolutions and, consequently, the output of the driving en gine is somewhat reduced. During the double drive the hydraulic transmission receives power and acts in an adjusting manner, preventing shocks and reducing the stress on and the wear of the friction discs, in contradistinction to conventional transmissions which involve considerable losses of power and also wear of clutch linings during the gear shifting operations.

In the opposite case, when connecting the hydraulic transmission, the clutches of the hydraulic transmission already begin to engage before the clutch for the direct drive disengages. The maintenance of tractive power obtained by such a construction of the control causes great advantages in the driving service, above all: uniform drive, quick shifting, omission of shocks, better acceleration of the vehicle than with conventional transmissions.

With the automatic shifting device, according to the invention, the gear change is effected automatically at the right moment (for instance always at the same speed or with the same torque to be transmitted). The gear changes are independent from the feeling, the attention, and the skill of the driver and he may attend fully to the road conditions, to other vehicles meeting or crossing his path, to road signs, etc.

As the working fluid remains in the hydraulic transmission and consequently may be worked at high temperatures, it can be cooled within the hydraulic transmission by a cooling jacket in the casing of the hydraulic transmission. This results in a remarkable simplification of the power transmission plant. here are no heat transformers outside of the hydraulic transmission, no transitions of working fluid from the hydraulic transmission to other places, and therefore no leakage losses, and there is no danger of tube damage as in most cases where it is necessary to arrange the hydraulic transmission and the cooling device at different places on the vehicle. The plant will be simplified in various respects. It is also possible to avoid any expenses for additional construction, for heating the fluid of the hydraulic gear during cold weather by means of the cooling water heated separately or by means of the idly running driving engine.

Due to the installation of a free-wheeling device, known per se, in case of damage of the driving engine, the latter may run at reduced speed, independent y of the power transmission, thereby preventing damage. According to the invention a speedier way of gear shifting and a simplification of the change speed gear is obtained by using the hydraulic transmission as a substitute for one or several of the usual braking devices for reducing the speed of the driving part of a clutch to produce the over-running condition aifording engagement of the clutch. This is effected according to the invention by engaging during a gear shifting operation, the clutch ahead the hydraulic transmission by means of a suitable control device. This braking efiect is much greater than that obtained with the conventional braking arrangements. Whereas the main-clutch must be disengaged with the latter arrangements to reduce the braking time, with transmissions according to the invention, using the hydraulic transmission as a retarding device, disengagement of the main clutch is not necessary, yet gear shifting can be quickly effected, because the high braking effect of the hydraulic transmission suffices not only to quickly brake the power transmitting parts within the change speed gear, but also the engine connected therewith.

The invention favors the use of a change speed gear having claw clutches the teeth of which have inclined front faces for engagement when overrunning, because such gears, aside from constituting an uncomplicated construction, afford an absolute safe and shock-proof gear shifting without special synchronizing clutches or other complicated and not absolutely reliable makeshift devices.

Other objects of the invention and details of power transmissions according to the invention will be described with reference to the drawing in which Figs. 1 and 2 diagrammatically illustrate two complete arrangements of power transmissions, according to the invention, partly in section.

Fig. 3 diagrammatically and mainly in section shows an example of a power transmission, according to the invention, for a locomotive driven by a diesel-engine, in the change speed gear of which, for simplification of the drawing, only four speeds are provided, a hydraulic transmission, a power flow dividing gear and an automatic gear shifting arrangement.

Figs. 4, 5 and 6 are cross sections along lines IV-IV, V-V, and VIVI of Fig. 3. Fig. '7 is longitudinal section through the slide valve 2&9 of Fig. 3 along line VII-VII of Fig. 8, the latter figure showing a cross section along line VIII VIII of Fig. '7. Fig. 9 is a longitudinal section through slide valve of Fig. 3 along line IX- IX of Fig. 11": which i lustrates a cross section along line X-2=Z of 9.

In Fig. 11 the complete arrangement of a further power transmission, according to the inven tion, is diagrammatically represented.

In Figs. 1 and 2 the numeral 5 designates an internal combustion engine driving a vehicle on rails, 2 a pressure oil pump attached to this engine, 3 a hydraulic transmission, 3 a mechanical change speed gear, 5, E and F friction clutches, 8 and 9 claw clutches. Numerals ii and i2 designate shifting cylinders for the change speed gear to which pressure oil is fed by pipe lines it and it from auxiliary power devices i5 and i6, respectively, according to the position of the operating devices I! and 28, respectively. Numerals 9 to 23 designate spur gears, 2 8 to 28, and St} to 3d designate shafts to be connected by means of the aforementioned spur gears and clutches. Numerals and 3B designate the axles of the vehicles, for which a driving wheel 3? is connected. Numeral 33 designates a gear shifting cylinder to which pressure oil is fed from the auxiliary power device i5 by means of a pipe line 39. ii? is an automatically operating free-wheeling device. Numerals 4i and i2 designate pressure oil pipe lines connecting the pump 2 and the hydraulic gear 3 which is kept filled constantly during normal operation.

With proper setting of the auxiliary power device, according to Fig. 1, shifting cylinder 38 alternately engages the clutch 6 and simultaneously disengages the clutch 5, or vice-versa, depending on whether the vehicle is driven by the hydraulic transmission 3 through gears i9 and 2t or by means of the mechanical change speed gear 4. When engaging clutch 6, claw clutch 8 arranged after the hydraulic gear 3 is also engaged by means of the auxiliary power device [5. After disengagement of the two couplings 6 and 8 for disconnecting the hydraulic transmission 3, the first speed of the mechanical change speed gear is operative for drive by the engaged friction coupling 5. The other speeds are thereafter controlled by the auxiliary power device l5 by means of the shifting cylinders H and I2.

Whereas in Fig. 1 the drive is performed through the hydraulic transmission 3 without the mechanical change speed gear 4, in the arrangement according to Fig. 2 the hydraulic trans mission 3 is arranged ahead or the mechanical change speed gear 4. Therefore, when the hydraulic transmission is operative the drive is transmitted through the first speed of the mechanical change speed gear to the wheel gear 23 and therefrom to the axle 36 of the vehicle.

The shifting cylinder 38 of Fig. 1 is provided in the embodiment, according to Fig. 2 inside of the auxiliary power device. In both cases the hydraulic transmission 3 is connected or disconnected by engaging or disengaging clutches 6 and t, or I and 8, respectively.

In Fig. 3 numeral 5! designates a shaft driven by the internal combustion engine, which shaft drives a shaft 55 through a free-wheeling coupling formed of two halves 5t and 53 which are compressed by a spring 5%. A gear wheel 56 is provided on shaft 55 and journaled in the casing 55?. There is an hydraulic transmission or torque converter 58 having driving part formed by a pump Wheel 59 and a driven part formed b a turbine wheel The hydraulic converter has a casing equipped with a jacket 6! through which the cooling water flows. 52 are teeth on the periphery of a planetary gear carrier 63 which comprises planetary pinions fit meshing with the ring gear E35 and the sun gear 66. There is a friction clutch half 6? to which a cylinder 68 containing a piston 6% is attached. it is a centre piece having a frictional lining li opposite to the coupling half 6i and having on its other side a frictional lining '52 adapted to cooperate with a coupling half "Ill. The latter is connected to a cylinder '58 adapted to slide therewith and enclosing a piston l9. The centre piece in is rigidly connected to the hollow shaft I3, piston 69 being rigidly connected to the planetary gear carrier 63 by means of hoialow shaft 8i. Piston E9 is ri idly connected to pump wheel 5t by a hollow shaft 82!. Inside of the last-mentioned shafts a shaft 32 is situated to which the turbine wheel pinion are splined. The latter meshes with wheel t l carrying on one of its sides half 35 of a free-wheeling claw coupling. Member cooperates with coupling half t6 slidably arranged on splines is? of a shaft ill and adapted to be shifted thereon against the pressure of a sprin' 85. There is a pinion 89 meshing with a spur gear wheel and being rigidly connected to the ring gear lltuneral Q2 designates a channel within a control casing 288. There are two pressure oil conduits 9i and communicating with interior annular grooves and 95, respectively, in a casing 3 t. These grooves also communicate with channels H21 and 322 of the hollow shaft 73 through radial bores I23 and I24, respectively; At their right hand ends the channels I2I and I22 have openings I25 and I26, communicating with the cylinders 68 and 18.

Wheel 84 is loose and wheel 90 is fast on shaft 91, which at its right hand end has rigidly fixed thereto a pinion 99 and has splined thereto, by means of splines 99, a shiftable coupling half I'0I. Pinion 99 together with gear wheel I09 forms a gear train of the change speed gear which comprises two additional pairs of gear wheels, I05, I06, I01, I08. The gear ratios of these 3 pairs of gear wheels are about 1:2, 1:125 and :1, respectively. Wheel I01 is rigidly connected to the driving shaft I02, extending to the right of the change speed gear, the left hand end of which shaft carrying a shiftable claw clutch half I83.

The individual speeds of the change speed gear are made up of the following gear wheels:

1. speed: 99I00-I08-I01 producing a gear ratio 1:4,

2. speed: I05I06I08I01 producing a gear ratio 1:25.

3. speed: 99-I00I06-I05 producing a gear ratio 1:1,6.

4. speed: direct.

The clutch halves I9I and I93 are activated by means of one arm of two-arm levers I09 and II I, the other arms of the levers being individually connected to the shiftable clutch halves III] and I I2 splined to shafts I I3 and I I4 which are rigidly connected to p-inions I09 and I08, respectively. The counterhalves H1 and H8 of the clutch halves I! and I93, respectively, are rigidly connected to pinion I05, the counterhalves H9 and I20 to the clutch halves I I0 and H2, respectively, being rigidly connected to pinion I86.

The claws of the clutches for the different speeds of the change speed gear, as is seen in the drawing, are provided with inclined front faces and immediately on disengagement of one clutch the shiftable half of the clutch alternately cooperating with th first clutch is brought into contact with its counterhalf, engagement being effected at the moment at which the originally slower rotating half begins to over-run the mating half. Over-running may be effected more quickly by conventional auxiliary shifting devices (braking one coupling half or accelerating by increasing fuel supply to the engine).

In the illustrated device the hydraulic transmission is used as auxiliary device for braking the clutch half. For this purpose a valve I21 is provided, operating under the action of a spring I28 and having a transverse channel I29 and a longitudinal groove I30.

I3I is a fuel supply control lever cooperating with a segment I32 and connected to a cylinder I34 by means of a rod I33, in which cylinder a piston I 31 is situated between springs I 35 and I36. Piston I31 is connected to a rod I4I one end of which is connected with a double lever I38, I39 adapted to control a fuel pump I40. A piston I42 slidably arranged inside of casing I43 is connected with the lower end of rod I4I. Piston I31 and cylinder I34 are adapted to be moved simultaneously with the fuel control lever I3I; cylinder I43 is stationary and is connected by conduits I41 and I49 to a casing I49 in which a valve I50 is slidably arranged and pressed to the right by means of a spring II. To the casing I49 are also connected conduits I52 and 211.

There is a pinion I55 fast on shaft 55 for driving a gear wheel I56 on a shaft on which centrifugal governors I6I and I62 are arranged adapted to operate valves I63 and I64, respectively, which are situated inside of cylinders I65 and I66, respectively. Governor I6I with valve I63 is for shifting to higher speed and governor I62 with valve I64 serves for shifting to lower speed. By suitably dimensioning compression springs I61 and I68 the speeds are determined for changing to higher or lower speeds. I69 and I10 are annular cavities in the valves I63 and I64, respectively. There are openings HI and I14 in the cylinders I65 and I66, respectively, connecting to the outside. I15 is a longitudinal groove in the valve I64. I11 and I18 are cylinders connected to the valve cylinders I65 and I66, respectively, by means of conduits I19 and I80, respectively. Cylinders I11 and I18 contain pistons I8I and I82, respectively, adapted to slide therein against the pressure of springs I83 and I84. Pistons I8I and I82 are connected to ratchet wheels I89 and I90 by means of rods I and I86 and pawls I81 and I88, respectively, pivoted thereto. The ratchet wheels are fast on the axle E9I of a cam shaft I93 inside of easing I92. There is a pressure pipe line I96 branching into lines I91 and I98 leading to valve casings I65 and I66, respectively.

Numerals 20I, 202 and 283 designate cylinders in the valve casing 200 in which control valves 205, 206, 201 are adapted to be moved by means of grooves 209, 2l0, 2I I, respectively (Fig. 4, Fig. 5, Fig. 6), of cam shaft I93 against the pressure of springs 2I3, 2I4, 2I5', respectively. There is a transverse channel 208 and there are openings 2I6, 2 I1, 2I8 connecting the spaces inside of the valve cylinders with the outside. 2I9, 220, 22I are annular cavities on the valves 205, 206, 201, respectively. There is a pressure oil feeding line 225 branching into lines 226 and 221. Line 226 connects to casing 200 and there is a continuation thereof in the form of a bore 228 extending through the casing 200 and communicating with the cylinder bores 20I, 202, and 203. Conduits 9I and 92 communicate with the interior of cylinder 203, conduits 23I and 232 with that of cylinder 202, and conduits 233 and 234 communicate with the interior of cylinder 20I.

To double levers I09 and III the ends 235 and 236, respectively, of piston rods 243 and 244, are connected and adapted to be moved by pistons MI and 242, respectively, sliding inside of cylinders 231 and 238. The end portions 235 and 236 are provided with slots 245 and 246, respectively, adapted to guide pins provided on levers I09 and III. Pistons MI and 242 are connected to valves 249 and 250 sliding inside of valve casings 241 and 248 connected to cylinders 231 and 238, respectively. Slide valve 249 is provided with transverse bores 25I to 256. Slide valve 250 has transverse bores 26I, 262, as well as angular channels 263, 264, and 265 (Fig. 9) and longitudinal grooves 251 and 258 (Fig. '7). 21I to 211 are connecting lines, 280 (Fig. 9) is a pressure oil feeding line. 290 is a channel in valve casing 241. There are channels 295 (Fig. 3') and 296 (Fig. 9) in the valve casing 246, and connecting openings to the outside 28I, 282 (Fig. 3), 283, 284 (Fig. 9). 293 (Fig. 7) is a control channel, 29I and 292 are control ports communicating with the channel 290.

30I is a control valve inside of a-casing 302. Valve 30I can be moved against the pressure of spring 303. There are angular channels 301 and 308 in valve 30I. 3 is a connecting line. Numeral 3I3 designates a conduit branching off from line 212. From line 21! short branch lines 3! and H5 lead to valve casing 302.

305 is a cross channel and 306 a longitudinal groove in valve itii. There are openings 3 l6 and 3!? in the valve casing 302 and openings 358 and 3 E9 in the casing of valve I50 for connecting the interior of the valves with the outside.

Cam shaft H93 may be rotated clockwise from the position shown in Figs. 4, 5, and 6. When the position of the cams coincides with line W, power is transmitted through the hydraulic transmission. Lines 1, II, III, IV indicate the positions of the cams in the 1st, 2nd, 3rd, or 4th mechanical speed.

Starting The different parts of the arrangement are represented in Figs. 3 to 10 in the positions which they occupy immediately after the internal combustion engine i has been started by suitable setting of the fuel pump M by means of the fuel control lever GEM, starting having been effected by means of conventional starting means. Parts :33 to I31, i il and M2, remain in the shown positions relatively to each other. By means of a pump, not shown, pressure oil is fed into lines its, 225, and 2% and flows from line 5% into lines it? and W8 and from line 225 through conduit 226 to channel 228 and through line 22? to the casing 241 of valve 2% and through channel 2%, part 292, channel 254. of valve 249, line 275, and channel 295 in casing 248 into the angular channel 263 in valve 258.

Lines 276 and 276, by channels 252 and 256, and openings 28! and 2&2, respectively, are connected to the outside and are without pressure. Consequently, no pressure is transmitted from line 2H through channel 26 and line 2?!) to the chamber of cylinder 3232 to the right of valve 3! and also no pressure is transmitted from line 216 through channel 2E2 and lines 213 and M3 into the chamber inside of casing 3612 to the left of valve 36?. No pressure is transmitted through line 3l3, chanel 3t? and line 3!! into the chamher to the right of valve 52?. Valves 36% and i2! are in their extreme right positions due to the pressure of springs 3% and i278.

Line P52 is connected with the outside through the angular channel 3% of valve 3M and opening 3H. Consequently, the chamber in casing I49 to the right of valve ltli as well as line It! are Without pressure. Valve I50, therefore, clue to the pressure of spring l5: will rest in its right hand end position.

Line 2T1, as is seen in Figs. 7 to 10, is connected with the outside through groove 258 in valve 259, line 2713, angular channel 265 in valve 250, and opening 234. Consequently, the space in casing M3 underneath of piston M2 is also Without pressure, as it is connected to line 21'! by means of channel 305 of valve Hit and by line M6. Because of line Ml, which, as explained, is also without pressure, the space in casing M3 above piston M2 is also without pressure. Piston M2, connected by rod Mi to the fuel control arrangement, therefore, follows to the movement of the fuel control lever.

Cam shaft W3 is in the position shown in Figs. 4, 5, and 6. Valves 2% and 201 are in their lower end positions, while the end pin of valve 205 has entered the groove 209 of cam shaft 893 so that valve 205 is situated in its upper end position. From groove 220 of valve 2% pressure oil is fed by means of line 232 to cylinder 23! to the right of piston 2M (Fig. 3), so that the latter is held in its left hand end position. In the illustrated positions of pistons 2M and 242 and of rods 2A3 and 244, clutches Illl, iii, and E03, H8 are disengaged by means of levers Hi9 and ill and clutches liil, H9 and Ht, we are engaged, the slidable halves of the clutches being rigidly connected by means of levers site and iii with those of the clutches iill, ill, and M3, M8, respectively. This causes the first speed of the change speed gear to be effected by means of pinions 99, iflil, ma, ml.

The pressure oil fed into groove tilt of valve 2M via channel 223 flows through channel 92, channel tilt of valve i2? and line 93 to groove 96 in casing M and therefrom through port I'M, channel iii, and the opening I25 to chamber l3. Due to the oil pressure in this chamber coupling half ii is moved into contact with middle portion iii. The power transmission from the internal combustion engine i is effected over free wheeling device 52, 515, shaft 55 and gear wheel 56 to the toothed wheel rim 62 of the planetary gear carrier 83 and therefrom through the planetary pinions Gd to the ring gear 65 and to the sun gear @315. A portion of the driving power is transmitted to shaft 97' by means of pinion 39 connected to the ring gear 65 and by means of gear wheel Q6. The portion of the driving power transmitted by the sun gear 66 is transmitted by the hollow shaft "it to middle portion It and by the coupling half Ti and the hollow shaft portion 32 to pump wheel 59 of the hydraulic gear. This portion of the power is transmitted by means of turbine wheel 6Q, shaft 30, gear wheels 83, 8d, and free-Wheeling coupling 85, also to shaft Q'l. The two power portions drive the first pinion 99 of the change speed gear and the power is transmitted to driving shaft M2 by means of the first speed of the change speed gear.

The vehicle, consequently, starts and the driving velocity increases to such a degree as the driver increases power production by means of the fuel control lever i3i. At first the larger portion of the driving power is transmitted through the hydraulic transmission. With increasing total power and increasing driving velocity the share of this power portion decreases and the power portion transmitted merely mechanically by means of the ring gear 65 increases.

When the number of revolutions per minute of shaft 55 reaches a predetermined lower limit while operating in a mere mechanical speed, valve lt l moves from its left hand position into its right hand position, because the weights of centrifugal governor H62 do not produce enough resistance to the spring E68 and move to their inner position. When, upon acceleration of the vehicle the aforementioned lower limit of the number of revolutions of shaft 55 is exceeded, valve I64 is shifted from its former right hand position into its left hand position. This very quickly occuring movement causes interruption of the former connection of line i893 with the outside through groove H5 and, for a moment, line 88b is connected with the pressure oil feeding line I98 through the groove ill], but at further increase of the speed of shaft 55, this connection is again interrupted. Consequently, for a moment, by means of line E89 pressure oil is admitted through conduit are above piston ltZ, but a possible downward movement of this piston is not followed by a rotation of ratchet wheel I90, because a further anticlockwise rotation (when looking from left to right in Fig. 3) beyond the illustrated position (for shifting to a still lower speed) is prevented by abutments not visible in the figure.

As a control arrangement of a similar kind for a change speed gear with clutches having overrunning claws is described for instance in the German Patent No. 662,084 and also in the U. S. A. Patent No. 2,086,725, it does not seem necessary to describe all speed changes. In the following the changes from the first to second, from the second to the third, as well as from the fourth to the third, and from the third to the second speed are described.

Changing into a merely mechanical drive When reaching the upper speed changing limit of the driving engine which, for instance, may correspond to a velocity of the vehicle of about 40 km./h., the centrifugal governor I6l shifts valve I63 into its right hand position in which it eifects, after having closed opening I1I, connection of the upper space in cylinder I11 with the pressure oil feeding line I91 through line I19 and groove I19 and groove I69. Thereby, piston I8I is moved downward against the pressure of spring I83 and rotates cam shaft I93 by means of pawl I81 and ratchet wheel I89. As seen from the left, the rotation is clockwise and amounts to of one revolution, so that the lines I in Figs. 4, 5, and 6 are now in the vertically downward position which was previously occupied by the lines W.

This rotation of cam shaft I93 does not change the position of the valves 265 and 206. The pistons 241 and 242 remain in their positions and the first speed remains engaged in the change speed gear. Since there is no pressure in casing I49, valve I553 remains in its right hand end position. Pressure is transmitted from line 221 via line 215 only to channel 253 of valve 256, and, since line 211 is connected by means of groove 258 of valve 249 (Fig. '7) to line 213 and since the latter line is connected by means of cross channel 265 of valve 256 (Fig. 9) with the opening 284 and thus to the outside, line 211 and, consequently, channel 395 of valve I50, line I46, and the space in cylinder I43 below piston I42 are without pressure.

The space inside of casing I43 above piston I42 is also without pressure, because line I 41 and line I52 connected thereto are connected with the outside by means of the angular channel 368 of valve 331 and port 311, valve 3M being held in its right hand end position by means of spring 303. Line 3I'5 terminating in the casing 332 beyond the right end of valve SIJI is connected with the outside by means of line 219, cross channel 264 of valve 253, line 214, cross channel 252 of valve 249, and port 281.

Due to the rotation of cam shaft I93 the end of the pin of valve 201 has entered the groove 2| I of cam shaft I93, causing connection of channel 92, which so far has been supplied with pressure fluid through channel 228, with the outside through the opening 216. Simultaneously, line 9!, which so far terminated above groove 22! of valve 291 and has been connected with the outside by means of channel 298, is now connected to the pressure fluid supply conduit 225 through groove 221, channel 228, and conduit 226. Channel 92 is connected with conduit 93 by means of cross channel I29 of valve I21, which is in its right hand end position. Conduit 93 is connected with the part I24 by means of groove 96 in casing 94, port I24 communicating with channel I22 in hollow shaft 13 and through port I26 with the space 18. Space 13, therefore, is without pressure so that the coupling half 11 is no more pressed against the middle portion 10. Consequently, pump wheel 59 of the hydraulic gear is not driven any more.

At the same time, pressure oil is fed from line 9| to space 63 through the groove 95 in casing 94, opening I23, channel 12!, and opening I25, and presses the clutch half 61 against the middle portion 10. The planet carrier 63 connected to the friction clutch half 61 by means of hollow shaft 'SI may be rigidly connected with the sun gear 66 by pressing the clutch part 51 against the middle portion 19. The entire driving power is now transmitted from pinion 56 by means of the blocked planetary gearing to pinion 89, which drives gear wheel 9'3 and pinion 99 connected therewith. The power'transmission, consequent- 1y, is effected merely mechanically by means of the first speed of the change speed gear. Whereas prior to the changefrom the hydraulic power transmission to the first mechanical speed transmission the driving engine rotated at greatest speed, the speed is now reduced by the difference between the primary and the secondary speed previously effected by the'hydraulic torque converter and then increases again with increasing driving velocity.

By a suitable design of valve 201 (thickness of the upper disc of valve 231) and, consequently, of the control of fluid flow in conduits 9| and 92 disengagement of clutch 1U, 11 and engagement of clutch I0, 16 may be effected so that no, however short relief of the driving engine will occur, the mere mechanical power transmission increasing at the same rate as the power transmission effected by the hydraulic torque converter decreases. 9

The wheel 84 is no longer driven by the shaft 89 through pinion 83. Free wheeling device 85-36 interposed between wheel 84 and shaft 91 permits retardation of the speed of wheel 84 relatively to the speed of shaft 91 which is driven by the wheel 93.

Change from the first into the second mechanical speed When the engine resumes top speed, the weights of the centrifugal-governor I6I move 'outwardly, shifting valve I63 from its left hand into its right hand end position, and oil pressure is again transmitted above piston I8I, as described. Cam shaft I93 is rotated againfor of a revolution so that the lines II in'Figs. 4, 5 and 6 point downwards. Theflposition of valves 265 and 201 does not change thereby and clutch 61, 19 remains engaged, iston 242 remains in its right hand end position and claw coupling I20, I12 remains engaged.

Valve 236, because of groove 213 on cam shaft I93, moves from its lower position, in whichit' had been until now, to its upper end position (Fig. 5). Feeding of pressure fluid from line 226'through channel 228 and groove 229 to line 232 is interrupted, the latter being connected by opening 2 I1 to the outside so that the space to theright of piston 2M in cylinder 23'? is without pressure. Line 23I, however, is connected through the recess 229 in valve 206 to channel 228 and the space in cylinder 231 to the left of piston 24'! is supplied with pressure oil, causing piston '24I to be moved from its left hand end position to the right, whereby the clutch part IIIl is disengaged from the clutch half H9. At the same time, the previous connection between1ines221 andl215 through channel 254 of valve 249 is interrupted. Opening 282 is closed by means of valve 249. The connection of line 213 to line 21'! through groove 255 of the valve 249 is interrupted (Fig. 7) at the beginning of the aforedescribed movement and condut 212 is connected to line 22'I by means of groove 29!]. Thus, pressure fluid is fed to the space underneath the piston I42 in casing I43 by means of line 2'I'I, channel 355 of valve I50 and line I25. The space above piston I42 in casing M3 is connected to the outside by means of line I 11 and I52, angular channel 3218 of valve 3M, and opening 3H, and is without pressure. The rod I II is shifted upwardly against the pressure of spring I35 and the fuel pump MI), by means of double lever I38, I39 is set for idling. Valve 30! is kept in its right hand end position, although during the disengagement of coupling I I0, I I9 pressure fluid may enter in front of valve 3M via lines 2' and M5 from line 227 and through groove 2%, control opening 29I and channel 253 of valve 249. This temporary connection with a pressure line does not cause a shifting of valve 31H. Upon disengagement of the clutch 1 I5, 2 I9, line 222 is connected by means of channel 252 of valve 229 via control opening 292 and groove 2% to the pressure line 221, so that valve 3! is held in its right end position by means of the pressure fluid fed into the space in front of the left hand end face of valve 3M and by the pressure of spring 203. Thus, pressure fluid may flow from line 3I3 via channel 307 of valve B ll into line 35 I. Consequently, valve I2! is shifted into left hand end position so that the connection between channel 82 and line 93 is interrupted and line 95 is connected to the pressure fluid feeding line 3II through groove I 30. The pressure oil fed from line 93 via groove 96, channel I22 and opening I26 into space "I8 engages coupling Ill, I'I so that the pumping wheel of the hydraulic torque converter is rotated. After disengagement of the claw clutch III), H9 the rotational speed of the claw clutch half HM and of the parts of the transmission connected therewith is rapidly reduced. It is not necessary to disengage the free-wheeling device 52 on shaft 55, because the speed of the motor is also reduced due to the braking effect of the converter 58. When the speed of the clutch part IIlI is reduced to the speed of the clutch part I I1 and the claws of part I I! overrun those of part ItI, the clutch IIJI, I I1 is engaged.

When the left hand control edge of channel 258 has reached the right hand control edge of line 271 (Fig. 7) the connection from pressure line 222 to line 217 via groove 2% is interrupted and line 21? is again connected to line 213 by the groove 25? in valve 242 and no pressure fluid enters line 27?. Upon continued movement of valve 249 to the right, conduit 217 is connected to the outside so that the space in casing I43 underneath piston I42, which communicates with line 2'I'I is again Without pressure and piston I42 moves into the position to which it was previously moved by manipulation of lever I3I. When the piston 2M and valve 249 are in their extreme right positions, line 216 is connected to the outside through channel 255 and port 282 so that channel 262 of valve 250, line 278, angular channel 301 of valve 3M, line 3, and the space to the right of valve I21 are without pressure and the valve I21 moves into its right hand end position, connecting the space I8 with the outside via channels H8, 92 and I29, line 93, groove 95, channel I22 and control opening I26, so that the clutch I0, TI is disengaged.

Change from the second into the third mechanical speed Upon reaching upper shifting speed, valve I63 operated by the centrifugal governor IBI causes further rotation of cam shaft I93, so that line III (Figs. 4-6) extends vertically downward. This does not change the position of valve 265. Valves 205 and 205 are moved from their upper into their lower end positions. This causes feeding of pressure fluid to lines 232 and 233 so that pistons 2M and 2 52 are moved to the left. Thus, in the manner described above, line 221 receives pressure fluid from line 221 through the grooves 290 and 258 (Fig. '7) and piston I52 is moved upwards so that the fuel supply to the engine is interrupted. Lines I4? and I 52 and the upper space of casing I53 are connected through the angular channel 352 and opening SI'I with the outside and are without pressure.

It does not matter which one of the two claw clutches which must be disengaged is disengaged first. It is assumed that both clutches (10!, II! and I20, II2) are disengaged simultaneously and that the front faces of the claws of the clutches H0, H9 and H8, I03 are adjacent, but reject each other. The two pistons MI and 242 are in corresponding positions (about half-ways of their stroke) and cause pressure fluid to be fed from line 221 via groove 2% and channel 253 of valve 249 into lines 2H and 365. This would cause movement of valve 3M to the left, if the conditions described in the paragraph below would not prevent it, and pressure fluid would be admitted to cylinder I43 from line 2' via line 2M, angular channel 358 of valve 525, lines I52, and I41 so that the piston I42 would be moved downward and the fuel supply would be increased. Simultaneously, the pressure fluid fed to casing I45 via line I52 would move the valve I58 to the left, so that the space below piston I42 in casing I43 is connected with the outside by means of line I46, groove 3% of valve I55 and opening 3 I 9.

Increase of fuel supply, however, is prevented, because valve 255 has also moved into its middle position and pressure fluid is fed from line 221 via channel 253 of valve 249 into line 215 and therefrom via the angular channel 253 of valve 250 into line 218 and by means of line 3I3 into the space of casing 362 to the left of valve am. The pressure acting on valve 3M towards the right together with the pressure of spring 303 is greater than the pressure exerted against the right hand end face of this valve. Thus, valve 30I moves into the right hand end position, as represented in the drawing. Consequently, pressure fluid flows into line 3H via line 3I3 and angular channel 367 of valve 35I and through valve I21 and line 93 into space It and causes. engagement of the friction clutch 70, TI. The braking effect of the torque converter causes a quick reduction of the rotational speed of the clutch half I It to be engaged, if clutch I5I, H1 is not yet disengaged. If clutch IIiI, II! is already disengaged, the speed of the wheel pair I56, I05 is quickly reduced, because of its small mass and because of the braking effect of the oil contained in the gear.

Clutch II 8, I03 will be the first one to be engaged and the piston 222 will be moved to its extreme left position. Since piston 2M is still in its middle position, the oil pressure in line 2II moves valve I into its left hand end position. Line 3| I is connected by the angular channels 301 with the opening 3I6 and is. without pressure. This causes shifting of valve I21 to the right and in. the manner described above disengagement of clutch 10, 11. Simultaneously, pressure fluid flows from line 3 I4, via angular channel 308 of valve 30I and lines I52 and I41 into the space above piston I42 in casing I43, so that the fuel pump is set for greater fuel supply to the engine, at the same time causing valve I50 to be shifted into its left hand end position and rendering the space of casing I43 underneath of piston I42 pressure-less by means of line I40, groove 306 and opening (H9. The rotational speed of the clutch half III] is thereby so increased that the clutch H0, H9 can be engaged and piston 24I together with valve 249 is shifted into its left hand end position.

The pressure fluid fed from line 280 (Fig. 9) when piston 242 is in its middle position, and through valve 250 into line 213 is ineffective while valve 249 is in its middle position, the pressure oil advancing only as far as the groove 251. After piston 242 has reached its left hand end position, line 213 comiected with the opening 283 by means of channel 265 is also without pressure, so that, when piston 24I has reached its left hand end position, no pressure fluid flows from line 213 to line 211.

Increasing the gear ratios.-Chdnge from the fourth to the third mechanical speed In the 4th speed piston MI is in its right and piston 242 is in its left end position. In the 3rd speed piston 242 is also situated in its left hand end position, whereas piston 24I has been shifted from its right hand into its left hand end position. These, as well as all other changes to higher gear ratios are initiated by the reduction of the engine speed to the speed which call for gear shifting and which causes dropping of the Weights of the centrifugal governor I52 and movement of valve I64 from its left hand into its right hand end position so that pressure fluid is fed from line I96 via groove I10 into line I80 which previously was without pressure, groove I10 in valve I64 having been connected with the opening I13. The fluid pressure moves piston I82 in cylinder I18 downward so that the pawl I88rotates cam shaft I93 anticlock-wise, as seen from the left in Fig. 3, from position IV into position III, line III in Figs. 4-6 being now in vertical position. This does not affect the positions of valves 205 and 201. Valve 236, however, moves from the recess '2I2 of the cam shaft E93 and, therefore, from its upper to its lower end position. Consequently, line 232 formerly having been without pressure is now fed with pressure fluid and line 23I is without pressure. When changing from the 4th into the 3rd speed, piston MI is moved to the left and causes the same change as during the second part of the change from the 2nd into the 3rd speed when the fuel supply is increased.

Change from the third to the second mechanical speed 3rd speed, by the centrifugal governor 'IGZ'a-cti vating valve I64 and so on, valve 2 01 remaining in its upper position, but valves 205 and 206 moving from their lower into their upper positions. This causes feeding of pressure fluid into line 23 I, formerly having been without pressure, while line 232 is connected to the outside; at the same time pressure fluid is fed to thepreviously pressure-less line 234 while line 233 is connected to the outside.

Assuming that the pistons MI and 242 have reached their middle positions corresponding to.

the position of. the clutch halves I'0I and H2 in which they are rejected from their counterhalves III. and I20, respectively, pressure fluid is fed from line 221 via channel 254 of valve 249 into line 212 and further on into line 3H and, after shifting of valve I21 to its left hand position, via channel I30 of valve I21, line 93, and channel I22 in hollow shaft 13 to space 18 so that the friction clutch 10, 11 is engaged, the torque converter reducing the rotational speed of the clutch half IOI. After engagement of the latter with the counterhalf II1 pressure fluid is fed via channel 253 of Valve 249, which is in its right hand end position, line 215, via channel 264 of valve 250, and lines 219 and 3I5 in front of the righthand end face of valve 30I, thereby pushing valve 30I into the left hand end position,

so that pressure fluid flows from line 3I4 via cross channel 308 of valve 30I and lines I52 and I 41 to the space of casing I43 above piston I42 and pushes this piston downward, increasing the fuel supply. Upon increasing the speed of the clutch half I20, clutch I20, H2 is engaged. Thereafter the operation is analogous to that during the change from the 2nd into the 3rd speed.

Change from the mere mechanical drive into the drive by the hydraulic torque converter The change into the drive by the hydraulic.

torque converter effected at a predetermined reduction of the velocity of the car by rotation of cam shaft I93 from position I into position W (line W being vertical in Figs. 4-6) does not cause a change of the positions of valves 205 and 20B. Consequently, there will be no movement of pistons 24-! and 246 and no shifting of the clutches in the change speed gear. But valve 201 (Fig. 6) will be moved from its upper into its shaft 13 and presses clutch half. 11 against the. middle. portion 10. This causes operation of the hydraulic torque converter.

Whereas with the mere mechanical drive in the 1st speed a definite speed of the internal combustion engine was maintained, cutting in of the hydraulic torque converter causes a difference in the speed of shafts 13 and 90. The driving shaft 91 of the change speed gear is driven merely mechanically by means of the ring gear 65 and the spur gears 89 and 90 are also driven by means of the hydraulic torque converter through the spur gears 83, 84. As 'longas there is a difference between the speeds of the gear wheels 84 and 90, free-wheeling device 85, 06 will stay disengaged. As soon as these wheels rotate at the same speed, the free-wheeling device will be automatically engaged.

Fig. 11 diagrammatically shows a part of an arrangement similar to that of Figs. 1, 2 and 3. Numeral I designates an internal combustion engine, 3 a hydraulic torque converter, 4' a change speed gear, 5 and 6' halves of a friction clutch, 8' a claw clutch, 9' a gear wheel on the motor shaft meshing with a gear wheel H1, and numeral H designates the middle portion of a double friction clutch connected with a shaft l2. There is a pinion E3 on a hollow shaft M connected to clutch half 5'. A clutch half 6 and a pump wheel i5 are connected to hollow shaft IS, a turbine wheel H as well as a gear wheel [8' being rigidly connected to shaft l9. Gear wheel H3 meshes with a gear wheel 20 loosely on shaft 2| to which it may be connected by means of claw clutch 8. Gear wheel 22'rigidly connected to shaft 2i-meshes with pinion I3.

Fig. 11 represents the principle of assembling a power transmission according to the invention having no gear for dividing the flow of power. There are two friction clutches, one half of each of which being mounted on a hollow shaft. The two friction clutches have a common middle portion. The shifting devices for the clutches and the speed changing gears are omitted in Fig. 11. When driving by means of the hydraulic torque converter and the spur gear 58', 20', friction clutch H, t and claw clutch 8' are in engagement, while for the mechanical drive by means of gears 13, 22 the friction clutch H, 5' is engaged.

We claim:

1. A power transmission system for vehicles driven by an internal combustion engine comprising, in combination, a drive shaft connected with the internal combustion engine, a mechanical change speed transmission, first mechanical power transmitting means connecting said drive shaft with said change speed transmission, said change speed transmission comprising a plurality of gear trains having different gear ratios, alternately operative claw clutches interposed between said gear trains for selectively connecting pairs of said gear trains for power transmission, each of said claw clutches having a pair of mating parts individually provided with claws having inclined front faces affording overrunning of the mating parts; a permanently filled hydraulic torque converter having a driving and a driven part, second mechanical power transmitting means connecting said first power transmitting means with the driving part of said converter, a friction clutch interposed in said second transmitting means, third mechanical power transmitting means connecting the driven part of said converter with said change speed transmission, a clutch interposed in said third power transmitting means, and automatic actuating means connected with said claw clutches and with said friction clutch, said actuating means comprising means for selectively engaging said claw clutches for consecutively connecting said gear trains to consecutively step down and step up the gear ratio of said change speed transmission, said actuating means comprising means to engage said friction clutch when said gear trains are connected for producing the greatest gear ratio of said change speed transmission.

2. A power transmission system as defined in claim 1, said hydraulic converter comprising a casing and a coolant circulating jacket in said casing.

3. A power transmission system as defined in claim 1 comprising speed responsive control means connected with said drive shaft and with said automatic actuating means for controlling the latter in accordance with the speed of said drive shaft.

4. A power transmission system according to claim 1 comprising a free Wheeling clutch interposed between the engine and said drive shaft.

5. A power transmission system according to claim 1, said automatic actuating means including means for engaging said friction clutch while said claw clutches are in neutral position prior to being engaged for shifting to produce a new gear ratio.

6. A power transmission system according to claim 1 comprising a second friction clutch interposed between said first and said second mechanical power transmitting means, and said actuating means comprising means for alternately actuating said two friction clutches.

'7. A power transmission system for vehicles driven by an internal combustion engine comprising, in combination, a drive shaft connected with the internal combustion engine, a mechanical change speed transmission, first mechanical power transmitting means connecting said drive shaft with said change speed transmission, a hydraulic torque converter having a driving part and a driven part, second mechanical power transmitting means connecting said first power transmitting means with the driving part of said converter, a first clutch interposed in said second power transmitting means, a second clutch interposed between said first and said second power transmitting means, third mechanical power transmitting means connecting the driven part of said converter with said change speed transmission, a third clutch interposed in said third power transmitting means, and automatic actuating means connected with said first and with said second clutch for alternately actuating said two clutches and including means affording a time lag between the actuation of said two clutches.

8. A power transmission system for vehicles driven by an internal combustion engine comprising, in combination, a drive shaft connected with the internal combustion engine, a mechanical change speed transmission, first mechanical power transmitting means connecting said drive shaft with said change speed transmission, a hydraulic torque converter having a driving part and a driven part, second mechanical power transmitting means connecting said first power transmitting means with the driving part of said converter, a first clutch interposed in said second power transmitting means, a second clutch interposed in said first power transmitting means, third mechanical power transmitting means connecting the driven part of said converter with said change speed transmission, a third clutch interposed in said third power transmitting means, and automatic actating means connected with said first and with said second clutch for alternately actuating said two clutches and including means for actuating said third clutch and affording a time lag between the actuation of said third clutch and the actuation of said first two clutches.

(References on following page) References Cited in, the file of this patent UNITED STATES PATENTS Number Name Date Feltz Aug. 1, 1916 Martin July 22, 1930 Lysholm Mar. 7, 1933 Martyrer Sept. 17, 1935 Durrell May 2, 1939 Dodge. Feb. 20, 1940 Bollinger May 13, 1941 Lysholm Oct. 14, 1941 Number Name Date Pollard Nov. 24, 1942 Kelley July 18, 1944 Voytech Apr. 1, 1947 FOREIGN PATENTS Country Date Great Britain May 30, 1933 Great Britain Feb. 1, 1940 France Sept. 3, 1942 France Feb. 27, 1943 France Feb. 21, 1944 

